Various constructions of rack and pinion type rotary actuators are known. For example, U.S. Pat. No. 3,246,581 to Carr illustrates one such construction. The actuator shown in the Carr patent has a rack assembly and a pair of pistons which are connected by pins in such a way as to form a lost motion connection, so that the pistons are free to float a limited distance relative to the rack assembly. The rack assembly includes a number of pieces which must be secured together. Such construction is relatively expensive to manufacture and assemble. Also, the pins must be removed whenever a rack is to be replaced.
One-piece rack and piston assemblies in rotary actuators are known. Constructions of this type are shown, for example, in Steiner U.S. Pat. No. 2,844,128, Meyer et al U.S. Pat. No. 3,156,160 and Carr U.S. Pat. No. 3,213,760. One piece rack and piston assemblies such as those shown in these patents are relatively inexpensive to manufacture compared to the multiple piece arrangement such as that shown in Carr U.S. Pat. No. 3,246,581 cited above. However, a floating piston is desirable for some services and one-piece rack and piston assemblies do not necessarily meet this requirement.